Jtag interface
#1
are the Jtag debug pin routed to any of the pins?

Roger
#2
Hi, it seems that the linux-sunxi guys have used this before: http://linux-sunxi.org/JTAG it is an adapter to attach a debug via the pins of the microsd card socket. If you compare that to the Pine schematic, the pins seem to be there: http://files.pine64.org/doc/Pine%20A64%2...elease.pdf so there could be a possibility to have JTAG access. The question is, what would you want to do with it? You can use the FEL mode bootloader via USB if you want off-board images running from your development box for example, or are you looking into bare-metal programming?

Maybe talk to the kernel developers over at #linux-sunxi at Freenode...
Come have a chat in the Pine IRC channel >>
#3
(06-26-2016, 07:05 AM)rmdo92 Wrote: are the Jtag debug pin routed to any of the pins?

Roger

The Jtag questions pop up several time. I have asked Sunxi community, they think Jtag is good to have but not a must. I currently collect the request and decide whether to includ eon next design. Please advise why you need the Jtag connection? and do you actually have the Jtag ICE?
#4
For the last few years (20+ years) I have been true real time, embedded (better than normal reliable) system, on the bigger system Linux.
This I normal do by "dropping" the file system and normal user interface, and take total control of want is running, normally a statically link app.

I take a few tries to do the switch to the app, from the kernel. The fastest way of doing this is with a Jtag debugger/ICE.

I do not like hardware debugger because of the odd problems they make.

(if there was a target pack for the STMC 2 would be nice, but I will have to make do with a more basic debugger)

Roger
#5
Can you provide a bit more details (and possibly links)? Does your RTOS run together with Linux (on different cores) and communicate with it?
#6
(06-27-2016, 04:48 AM)ssvb Wrote: Can you provide a bit more details (and possibly links)? Does your RTOS run together with Linux (on different cores) and communicate with it?

It is Linux, a few mods in init/main.c so it does not look on a file system for the init app, it is a know place is ram/flash, uboot can load them image in to ram for you.

if you look at how the Linux comes out of low power mode, you can see the basic way it does it.

you can not make Linux in to a true RTOS, but with a lot of playing around with, mainly playing with the IRQs, you can almost get there.

I have not done much with ARM based systems (that is 1 of the things I was going to be playing with the pine64 board)

I done the strictest timing on a G3 based system, with timings down to a few 10s of clock cycles, G3 Linux Kernel could take over 1000 clock cycles to handle an IRQ, that needs a 2 level IRQ code, 1 level outside Linux and only passing them Linux if needed.

(Playing with the low power code you can get fast boot as well, I think we got a full site box, to boot in less than a second and keys and decode channel on most channels in less that 10 seconds, main controlled by how the keys are managed on the channel.)


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